The subfield of electrical engineering that focusses on analysing, modifying, and synthesizing signals such as sound, images, and scientific measurements.
Questions tagged [signal-processing]
393 questions
62
votes
12 answers
Are there pure sine waves in nature or are they a mathematical construct that helps us understand more complex phenomena?
I've studied a bit of frequency analysis with FFT and optimal phase binning and was taught that we can represent any composite waveform as the sum of its component frequencies.
I understand the maths works and gives meaningful results that we can…
Schizomorph
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50
votes
3 answers
What would a blackbody sound like?
If a blackbody has a temperature such that its peak frequency was well within our audible range, for example $1\ \mathrm{kHz}$, what would that sound like if we used Planck's law to plot its spectral curve in the frequency domain and performed a…
ayane_m
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36
votes
7 answers
Why can't you hear music well over a telephone line?
Why can't you hear music well well over a telephone line?
I was asked this question in an interview for a university study placement and I unfortunately had no idea.
I was given the hint that the telephone sampling rate is 8000 samples per second.
Danny Rancher
- 499
24
votes
8 answers
Why a sine wave?
Whenever:
traveling or stationary waves on a string
electromagnetic radiations
sound waves
are put in form of a function, they are either represented as sinusoidal or cosinusoidal functions.
What's the reason behind choosing these trigonometric…
Kyathallous
- 1,006
23
votes
11 answers
How do computers store sound waves just by sampling the amplitude of a wave and not the frequency?
All of this just doesn’t make sense though.
I mean, doesn’t the amplitude represent the loudness and the frequency the pitch? Aren’t they completely independent from each other?
Is the book just lacking information or am I just not getting…
RedP
- 411
20
votes
6 answers
Can we quantify the pitch of a sound that is a mixture of many frequencies?
How is the pitch of a sound defined quantitatively when it is a mixture of many frequencies? For example, the sound emitted by a plucked guitar string, or say, the pitch of somebody's (normal) voice. I know that female voices are generally of higher…
Solidification
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20
votes
6 answers
Why are cosine and sine functions used when representing a signal or a wave?
Actually, in the mathematics sine and cosine functions are defined based on right angled triangles. But how will the representation of a wave or signal say based on these trigonometric functions (we can't draw any right angled triangles in the…
gayathri gayi
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19
votes
5 answers
Fourier vs. Laplace transforms
Electronics books often use Laplace to analyze circuits, while in physics we use Fourier, most of the times... if not always: from complex impedances to electromagnetism, quantum mechanics, Green functions, etc etc.
Various sources maintain that…
Ste
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16
votes
3 answers
How Earth communicates with Voyager I?
After taking a basic signals & systems class and learning about the frequency domain, I started wondering:
How the heck do scientists still communicate with Voyagers I and II??
Do they send/receive signals in a frequency that is otherwise…
user541686
- 4,311
15
votes
4 answers
Reconstruction of "wavefunction" phases from $|\psi(x)|$ and $|\tilde \psi(p)|$
Consider a "wavefunction" $\psi(x)$, which has a Fourier transform $\tilde \psi(p)$.
Suppose that we know, for each $x$, $|\psi(x)|^2$, and that we know, for each $p$, $|\tilde \psi(p)|^2$.
Have we enough information to reconstruct the…
Trimok
- 18,043
14
votes
10 answers
Why does a capacitor act as a frequency filter?
What is it about a capacitor which allows it to filter frequencies?
I understand the construction of a high-pass RC filter, and the mathematics behind it, but I'm struggling to find an explanation of the physics behind the phenomenon.
In my mind I…
gingerbreadboy
- 267
14
votes
2 answers
Convolutions in Physics
At a high-level Wikipedia states: "A convolution between two functions produces a third expressing how the shape of one is modified by the other."
But there are clearly many ways of combining functions to get a third one. A convolution is a specific…
Josh
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12
votes
3 answers
Avoiding radar detection using active noise control instead of a stealth fuselage
was reading about different stealth technologies used by modern aircrafts to avoid radar detection.
Wouldn't it be easier to have a receiver on the airplane listening on the radar frequencies and then re-transmit that same signal but phase shifted…
Henry Skoglund
- 131
12
votes
2 answers
Is there a fundamental limit to the temporal resolution of signals from space?
In Earth-based experiments, we can measure phenomenon very rapidly in an experiment given appropriate equipment. Clearly if something takes a long exposure to see (due to a weak signal), then the temporal resolution will be filtered by the exposure…
tpg2114
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12
votes
3 answers
Can the Kramers–Kronig relation be used to correct transfer function measurements?
In experimental physics, we often make measurements of linear transfer functions; these are complex-valued functions of frequency. If the underlying system is causal, then the transfer function must be analytic, satisfying the Kramers-Kronig…
nibot
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